Method of obtaining fluid samples from a well bore



June 7, 1966 1.. 1. JENSEN 3,254,710

METHOD OF OBTAINING FLUID SAMPLES FROM A WELL BORE Filed Nov. 13, 1963Z/a flav Zia -5 l A/oyo I de/wen INVENTOR.

ATTORNEY United States Patent I METHOD OF OBTAINING FLUID SAMPLES FROM AWELL BORE Lloyd I. Jensen, Calgary, Alberta, Canada, assignor toJohnston Testers, Ltd., Alberta, Canada, a corporation of Canada FiledNov. 13, 1963, Ser. No. 323,490 Claims priority, appligrtigraganada,July 2,- 1963,

6 Claims. (:1. 1663) end of a string of pipe or tubing. After packingofi or isolating the {formations to be tested from the well controlfluid (usually called mud), the tester valve is opened so that anyfluids from the formations may flow into the spring of tubing. Thus whena fluid flow occurs, there are clear visual indications at the surface.

It is well know that much exploration is conducted under utmost secrecy.For this reason, when conducting a drill stem test on a well it ishighly desirable to maintain the results of the test strictlyconfidential.

In accordance with the present invention, in a drill stern test, thefluid recovery is limited to a given sampling section of the drill pipewhich is closed off prior to retrieving the sampling section at theearths surface. The closed off sampling section when retrieved isseparated into individual sample containers which are usually a lengthof drill pipe. Into each end of a drill pipe prior to separation, aneutral displacement agent is injected to displace any trace of fluidrecovery from the ends of the pipe and the pipe ends are sea-led beforeseparation. Thereafter, upon separation, the fluid recovery in a sealedpipe length can be transported to any suitable or desired location forexamination in the privacy of a laboratory.

Apparatus in accordance with the present invention includes endconnections called subs which attach to'the joint of the pipe and to oneanother. Means are provided for injecting a neutral displacement agentto the interconnection between coupled subs and sealing off the passagesin the subs after the fluid sample has been displaced.

Accordingly, it is an object of the present invention to provide new andimproved apparatus and methods for conducting drill stem tests where theresults of the test can be confined between sealed ends of a containeror length of-drill pipe.

Still another object of the present invention is to provide new andimproved methods and apparatus for conducting drill stem tests to obtaindiscreet fluid samples between the ends of a length of drill pipe.

The novel features of the present invention are set forth withparticularity in the appended claims. The present invention, both as toits'organization and manner of operation together with further objectsand advantages thereof, may best be understood by way of illustrationand example of certain embodiments when taken in conjunction with theaccompanying drawings in which:

FIG. 1 illustrates a string of tools in a well bore for practicing thepresent invention;

FIG. 2 illustrates a view in cross-section of apparatu embodied in thepresent invention; and

FIG. 3 is a view taken along line 33 of FIG. 2.

FIGURE 1 illustrates apparatus embodying the inven tion where a drill ortubing string 11 is lowered from the surface of the earth into a wellbore 12. At the lower end 3,254,710- Patented June 7, 1966 of thedrillstring 11 is a conventional testing tool string 13 such as the typeillustrated and described in U.S. Patent Number 2,901,001. The usualdrill stem testing tool string 13 includes a flow tube with anormally-closed valve (not shown) and a packer element 14. The packerelement 14, when actuated, expands into sealing engagement with theborehole wall. After the tester valve is opened, fluid flows from belowthe packer 14 through its flow tube and into the tubing string. Pressurerecorders (not shown) in the tool string 13 measure and recordpressures. As shown in FIG. 1, a perforated anchor 15, for admittingwell fluid to the flow tube is also used for engaging the bottom of thewell bore for expanding the packer in a conventional manner.

It will be appreciated that hook-wall packers (not shown) which can beset without a bottom hole anchor could be employed rather than the typedescribed.

In the present invention, one or more of the tubing strin-g sections1618 adjacent to the tester 13 are separated from one another by a pairof -releasa-bly connected isolation subs A and B. These isolation subs,as will hereinafter be more fully explained, serve to enclose within theends of a section of tubing a fluid sample so that there is no externalindication of the presence or absence of fluid when the subs aredisconnected at the surface. The enclosed fluid samples then can besafely transported to any suitable location for a private examinationand analysis.

Referring now to FIGURE 2, each isolation sub A and B has a similarconstruction including threaded box and pin ends 19 and 20 forconnection in a string of tubing. Each sub has similar longitudinal flowpassages 21a and 21b extending longitudinally through the respectivesubs are each has a similar valve 22a and 22b provided for therespective passages. Valve 22a, shown in its normally open position, hasa body portion 23a threadedly received in a valve bore 24a and has atapered valve portion 25a provided with 0 rings. When the valve body 23ais rotated, the valve portion 25a seats in a valve seat 261: in a subunit to block or close off the fluid passageway 21a. Rotation of thevalve body 23a is accomplished by means of a wrench or the like appliedto the body 23av through a cylinder bore 27a opening to the exterior.Thus, the valve has -a control portion exposed to the exterior of thesub. The body portion 23a (if a valve 22a is provided with an O ring toseal within a cylinder bore 27a. A snap ring 28a received in a snap ringgroove pre vents the valve body from leaving the valve bore 27a. Valve22b has a similar arrangement.

The lower sub unit B is provided with another Valve 30 (FIG. 3) whichcontrols fluid flow to a passageway 31 B and into the various sections16-18 of tubing string.

in fluid communication with and opening to the longitudinal passageway21b. The valve 30, which is normally closed, includes a body 32threadedly received in a bore 33 with a valve element 34 having 0 ringsproviding a seal with a valve seat 35 in the sub. The valve body 32similarly is provided with an O ring 36 and snap ring 1 retainer 37 andsimilarly is controlled from the exterior of the sub. Another transversepassage 38 opens midway of the valve body 32 and is connected to aconventional pressure fitting unit 39. When the valve 30 is opened, asby unthreading of the valve body, the pressure fitting 39 and thetransverse bore 31 are placed in fluid communication.

In the apparatus as thus far described, well fluid can flow through :thetester 13 through the sub units A and At the upper end of the testingsection above the uppermost isolation sub, a relief valve 40 isprovided. As shown in FIG. 2, the relief valve 40 includes a generallycylindrical housing 42 with a longitudinally extending bore 43 havingupper and lower counterbore sections 3 44 and 45. In the lower end ofthe housing 42, the counterbore 45 is closed by a ported plug 46 whichhas an upwardly facing valve seat 47. An undersized cylindrical element48 is disposed within the lower counterbore 45 and has a downwardlyfacing valve surface 49 provided with an O ring. A spring element 50 isprovided to normally urge the cylindrical element 48 to a positionclosing the port in the plug 46. When the cylindrical element isdisplaced from the plug 47, the annulus 51 between the cylindricalelement 48 and counterbore 45 permits a fluid bypass. The cylindricalelement 48 is provided with upstanding spacer elements 52 to maintainthe bore 43 open when the cylindrical element 48 is pushed upwardly. Thecentral bore is connected by transverse ports 53 to the exterior of thehousing 42.

The trip or relief valve 40 has a plunger element 54 with portions 55and 56 respectively received in the upper counterbore 44 and centralbore 43. The plunger element 54 is held in the upper position by a shearring 57. A hammer portion 58 of the plunger element 54 when struck witha go-devil or the like dropped through a tubing string shears the ring57 and displaces or transfers the plunger portion 55 .to a secondposition. The portion 56 of the plunger in the central bore 43 isprovided with spaced ring seals 59 which straddle the transverse ports53 in the second position of the plunger and thereby close the portsfrom fluid flow. A depending portion 60 of .the plunger element isarranged to engage the upper end of the cylindrical element 48 in thesecond portion to limit downward travel of element 54 and insure theproper positioning of seals 59 to either side of ports 53.

In operation, the test tool string 13 is lowered into the well bore, atthe end of a string of tubing or pipe, the test valve of the tool string13 being closed. Above tool string 13 are sections of tubing 16, 17, 18each having a sub-unit A and B respectively secured to the ends.

Adjacent sub-units A and B are threadedly interconnected. At the top ofthe test sections of tubing, a relief valve 40 is connected above asub-unit A.

At the level where the test is desired, the packer is actuated intosealing engagement with the well bore and the test valve of tool string13 opened permitting formation fluids isolated below the packer to flowinto the tubing sections 164.8. The hydrostatic pressure of the wellfluid (mud) above the packer acts on element 48 in the relief valve tokeep the valve closed. Thus, a fluid sample is recoveredwithin sections16-18 only, the flow upwardly into the tubing string being prevented byrelief valve 40.

After permitting fluid to flow for a suitable period of time, the testvalve of the tool string 13 is closed thus closing off the ends of thesampling section and the packer disengages from the well bore.

While the tubing string is being retrieved from the well bore, if thepressure of the fluids within sections 16-18 exceeds the hydrostaticpressure, the relief valve 40 allows the fluid under pressure in thetubing sections 16-18 to bleed off into the annulus. Because of thelarge volumes of mud, this bleed off is but a trace and does not revealthe test results. At a point where the relief valve is about 100 feetbelow the surface, a godevil is dropped through the tubing string andengages the hammer element in the relief valve to retain the reliefvalve in a closed position. The seals 59 of the relief valve thuspositively close off ports 53.

The relief valve and first subs A and B are then brought to the surfacewhere they are available for disconnection. At this point, valve 30 isopened and a grease gun or any other source containing a neutraldisplacement agent is connected to the pressure fitting 39. Grease isinjected to displace any fluids between subs A and B. Following thisvalves 22a and 22b of subs A and B are closed. It is noted that it maybe desirable to sequence the steps as follows: initially close valve 22bof sub unit B and permit grease flow into passageway 21a of sub A; closevalve 22a of sub A; open valve 22b of sub B for injection of greasefollowed by closing of valve 22b of sub B.

After displacing the recovery fluid from the releasably interconnectedsubs A and B with a neutral agent, the threaded connection between thesub-units A and B is broken. The lower set of isolation on the joint ofpipe is then brought to the surface. Valve B is closed and as describedabove, a suitable neutral displacement agent is pumped via valve 30 todisplace any recovery fluid between the units through sub A. Thereafter,the valve 22a of sub A is closed, valve 22b of sub B is opened anddisplacement fluid injected followed by closing of valve 225 in sub B.The threaded connection between the sub-units A and B is then broken.

It will be appreciated that the disconnected section of tubing 18contains a fluid sample between subunits A and B at its opposite endsand no visual indication of the presence or absence of a fluid sample isgiven. Each section of the tubing is thus individually isolated andindividually sealed samples are obtained. Each individual sample in atubing string then can be transported to any desired location and thesample analyzed in privacy.

While a particular embodiment of the present invention has been shownand described, it is apparent that changes and modifications may be madewithout departing from this invention in its broader aspects and,therefore, the aim in the appended claims is to cover all such changesand modifications as fall within the true spirit and scope of thisinvention.

What is claimed is:

1. A method of drill stern testing in a well bore comprising the stepsof:

withdrawing a fluid sample from earth formations into a sampling sectionin a well bore; closing off the ends of said sampling section prior toretrieving the sampling section from the well bore; bringing the closedoff sampling section to the earths surface and separating said samplingsection into individual containers;

and prior to separation of said sampling section, in-

jecting a neutral displacement agent into each end of a separatecontainer todisplace any trace of fluid recovery from the ends of acontainer followed by sealing off of the ends of a container.

2. A method of drill stem testing in a well bore containing a well fluidcomprising the steps of:

packing off a section of the well bore from the well fluid for thepurpose of withdrawing a fluid sample from the earth formations whichare isolated from the well fluid;

placing said packed elf earth formations in fluid communication with astring of pipe having a sampling section including one or moreindividual lengths of pipe serially arranged where interconnectionbetween the ends of each length of pipe includes a pair of subsreleasably coupled to one another, each sub having a normally openclosure means permitting fluid communication theret'hrough;

closing off the sampling section at its lowermost and uppermost ends tocontain a fluid sample therebetween;

bringing a length of pipe of said sampling section to the earths surfaceand injecting a neutral displacement agent in the interconnectionbetween adjacent subs while said closure means are open and displacingany fluid sample therebetween, closing said closure means, anduncoupling said subs from one another.

3. A method of drill stem testing in a well bore containing a well fluidcomprising the steps of:

packing off a section of the well bore from the well fluid for thepurpose of withdrawing a fluid sample from the earth formations whichare isolated from the Well fluid;

placing said packed off earth formations in fluid communication with astring of pipe having a sampling section including one or. moreindividual lengths of pipe serially arranged where interconnectionbetween the ends of each length of pipe includes a pair of substhreadedly coupled to one another, each sub having a normally openclosure means permitting fluid communication therethrough; r

closing off the sampling section at its lowermost an uppermost ends tocontain a fluid sample therebetween;

retrieving said sampling section from the well bore while bleeding offpressure of the fluid sample in the sampling section in excess of thepressure of the well fluid;

discontinuing the bleeding off of pressure at a point while theuppermost end of the sampling section is still in the Well bore;

bringing a length of pipe of said sampling section to the earths surfaceand injecting a neutral displacement agent in the interconnectionbetween adjacent subs while said closure means are open and displacingany fluid sample therebetween, closing said clo sure means anduncoupling said stubs from one another.

4. A method of drill stem testing in a well bore containing a well fluidcomprising the steps of: packing off a section of the well bore from thewell fluid for the purpose of withdrawing a fluid sample from the earthformations which are isolated from the well fluid; opening a test valveto place the packed-off earth formations in fluid communication with astring of pipe having a normally closed sampling section and a sub atits lower end, the sub having a normally open closure means permittingfluid communication therethrough; closing the test valve to entrap afluid sample in the sampling section; closing the normally open closuremeans in the sub when the sub is brought to the surface and beforeuncoupling the sampling section from the string of pipe.

5. A method of drill stem testing in a well bore containing a well fluidcomprising the steps of: packing off a section of the well bore from thewell fluid for the purpose of withdrawing a fluid sample from the'earthformations which are isolated from the'well fluid; placing said packedoif earth formations in fluid communication with a string of pipe havinga sampling section including one or more individual lengths of pipeserially arranged where interconnection between the ends of each lengthof pipe includes a pair of subs threadedly coupled to one another, eachsub having a normally open closure means permitting fluid communicationtherethrough, the sampling section having normally closed valve meansatits upper end; closing off the sampling section at its lowermost end tocontain a fluid sample therein; retrieving said sampling section fromthe well bore and bleeding off excess pressure of the fluid sample inthe sampling section by opening said normally closed valve means;discontinuing the bleeding off of pressure at a point while theuppermost end of the sampling section is still in the well bore; closingthe normally open closure means in each sub as each sub is brought tothe surface and before uncoupling the subs from one another.

6. A method of drill stem testing in a well bore containing a well fluidcomprising the steps of: isolating a section of the well bore from thewell fluid for the purpose of withdrawing a fluid sample from the earthformations which are isolated from the well fluid; opening a test valveto place the isolated earth formations in fluid communication with astring of pipe having a sampling section, with its upper end normallyclosed by a valve rneans and a sub at its lower end, the sub having anormally open closure means permitting fluid communication therethrough;closing the test valve to entrap a fluid sample in the sampling sectionbetween the sub and the valve means; retrieving the sampling section tothe earths surface and relieving excess pressure in said samplingsection by operation of the normally closed valve; and closing thenormally open closure means in the sub when the sub is brought to thesurface and before uncoupling the sampling section from the string ofpipe.

References Cited by the Examiner UNITED STATES PATENTS 1,674,055 6/ 1928Nixon et al 166-224 2,092,338 9/ 1937 Spencer 166-142 2,132,072 10/1938Johnston 166-152 2,203,577 6/1940 ONeill et al 166142 2,364,464 12/1944Moore 166142 2,719,588 10/1955 Huber 166152 2,850,097 9/1958 Bloom 166-32,947,363 8/1960 Sackett et al 166--224 3,038,539 6/1962 Bloom et al.166-3 3,075,585 1/1963 Carlton et al l66-164 CHARLES E. O CONNELL,Primary Examiner. I D. H. BROWN, Examiner.

4. A METHOD OF DRILL STEM TESTING IN A WELL BORE CONTAINING A WELL FLUIDCOMPRISING THE STEPS OF: PACKING OFF A SECTION OF THE WELL BORE FROM THEWELL FLUID FOR THE PURPOSE OF WITHDRAWING A FLUID SAMPLE FROM THE EARTHFORMATIONS WHICH ARE ISOLATED FROM THE WELL FLUID; OPENING A TEST VALVETO PLACE THE PACKED-OFF EARTH FORMATIONS IN FLUID COMMUNICATION WITH ASTRING OF PIPE HAVING A NORMALLY CLOSED SAMPLING SECTION AND A SUB ATITS LOWER END, THE SUB HAVING A NORMALLY OPEN CLOSURE MEANS PERMITTINGFLUID COM-